The present invention relates to an improvement of the invention disclosed and claimed in the application filed by Geidies et al. Ser. No. 840,003 on Oct. 6, 1977. In this process, partial oxidation gases which contain dust-like pollutants are first passed into a dust separator where between about 70 to 95% of the pollutants are removed, whereupon the gases are then washed in a wet cleaner with an amount of water which is not larger than is necessary for eliminating the residual dust.
A cooling of the gases between the dust separator and the wet cleaner is provided only optionally in the earlier application. In that case, the gas should be cooled only to the extent that no condensation of steam occurs. The gas, as a consequence of this procedure, when entering the wet cleaner still has a temperature between about 70.degree. and 80.degree. C. corresponding to the dew point of the gas. If no intermediate cooling between the dust separator and the wet cleaner were provided, the temperature of the gases when entering the wet cleaner would even be higher. In the earlier application it is therefore contemplated that the gases which leave the wet cleaner and are largely freed of the dust pollutants are further cooled in a direct cooler by means of circulating water. The circulating water in this case is indirectly cooled.
It is, however, possible that in this procedure, due to the high wash water temperature in the wet cleaner and in the subsequent direct cooler (about 70.degree. C.) deposits may occur in the pipes and channels and a strong vapor may form above the settling basin which is provided for treatment of the discharged wash water.
Besides, the high entry temperature of the gas at the wet cleaner has also been rather undesirable in the earlier process. The reason is that because of the high gas temperature a relatively large gas volume must be processed which in turn requires correspondingly large dimensions of the wet cleaner. This causes the investment and operating cost of the device to be fairly high.
It is therefore an object of the invention to further improve the earlier process by avoiding the just-described difficulties and at the same time to lower the investment and operating cost of the process.